[Solved] Given the following Spring Boot method with Redis caching: @Cacheable("books") public Book findBookById(Long id) { System.out.... } What will be printed if findBookById(1L) is called twice in a row? | Spring Boot

Spring Boot - Caching

Given the following Spring Boot method with Redis caching:

@Cacheable("books")
public Book findBookById(Long id) {
    System.out.println("Fetching from DB");
    return bookRepository.findById(id).orElse(null);
}

What will be printed if findBookById(1L) is called twice in a row?

AFetching from DB

BNo output

CFetching from DB Fetching from DB

DError at runtime

Step-by-Step Solution

Solution:

Step 1: Understand @Cacheable behavior
The first call caches the result and prints "Fetching from DB".
Step 2: Analyze second call output
The second call returns cached data without executing method body, so no print.
Final Answer:
Fetching from DB -> Option A
Quick Check:
Cache avoids repeated DB fetch print [OK]

Quick Trick: First call prints, second uses cache silently [OK]

Common Mistakes:

Expecting print on every call
Thinking cache disables method
Assuming runtime error due to caching

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More Spring Boot Quizzes

Given the following Spring Boot method with Redis caching:

Step 1: Understand @Cacheable behavior

Step 2: Analyze second call output

Final Answer:

Quick Check:

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